When he was given a metal detector for Christmas, seven-year-old Sonny Carter hoped to find buried treasure.

He tried it out on Boxing Day – and within 15 minutes the machine began bleeping.

Sonny found a heavy metal object caked in mud, which he dug up and took home. But as his father Jem Carter, 37, rinsed it in the sink, he realised it looked like an unexploded bomb.

The family alerted police and a bomb disposal team raced to their home in King’s Lynn, Norfolk. They examined the 11.5lb device and said it was an RAF practice bomb from the Second World War – which luckily did not contain explosives.

Amazing discovery: Sonny Carter, seven, was out walking with his brother Marley, nine, and their parents when he found a 10lb bomb with his new metal detector

Sonny's relieved mother, Tracey Wood, said today that, despite the drama, she was impressed that her son's National Geographic present had worked so well.

She said: 'We are dumbfounded that he discovered this on his first go.

'We are going to go out again to see if he can find something Roman. It has made our Christmas.